Module: ActiveRecord::Acts::Tree::ClassMethods
- Defined in:
- lib/active_record/acts/tree.rb
Overview
Specify this act if you want to model a tree structure by providing a parent association and an children association. This act assumes that requires that you have a foreign key column, which by default is called parent_id.
class Category < ActiveRecord::Base
acts_as_tree :order => "name"
end
Example :
root
\_ child1
\_ sub-child1
root = Category.create("name" => "root")
child1 = root.children.create("name" => "child1")
subchild1 = child1.children.create("name" => "subchild1")
root.parent # => nil
child1.parent # => root
root.children # => [child1]
root.children.first.children.first # => subchild1
Instance Method Summary collapse
-
#acts_as_tree(options = {}) ⇒ Object
Configuration options are:.
Instance Method Details
#acts_as_tree(options = {}) ⇒ Object
Configuration options are:
-
foreign_key
- specifies the column name to use for track of the tree (default: parent_id) -
order
- makes it possible to sort the children according to this SQL snippet. -
counter_cache
- keeps a count in a children_count column if set to true (default: false).
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# File 'lib/active_record/acts/tree.rb', line 35 def acts_as_tree( = {}) configuration = { :foreign_key => "parent_id", :order => nil, :counter_cache => nil } configuration.update() if .is_a?(Hash) belongs_to :parent, :class_name => name, :foreign_key => configuration[:foreign_key], :counter_cache => configuration[:counter_cache] has_many :children, :class_name => name, :foreign_key => configuration[:foreign_key], :order => configuration[:order], :dependent => true module_eval <<-END def self.roots self.find(:all, :conditions => "#{configuration[:foreign_key]} IS NULL", :order => "#{configuration[:order]}") end def self.root self.find(:first, :conditions => "#{configuration[:foreign_key]} IS NULL", :order => "#{configuration[:order]}") end END define_method(:siblings) do if parent self.class.find(:all, :conditions => [ "#{configuration[:foreign_key]} = ?", parent.id ], :order => configuration[:order]) else self.class.roots end end end |